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so it whould be the cats that are to cold ? or just not the temp the ecu whants to see we are pricing out what it whould take to replace all heat shieds on one of theese cars to get a idea if its even fesabble to fight thiss code or leave it be

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how cold is it in summer where you are?

 

I kinda don't see how ambient temps have much to do with this. Those heat shields are partly to prevent hot exhaust parts from setting fire to grass if the car is parked off-pavement. Also to shield nearby stuff like oil filters, wires, cables w'ever.

 

if an exhaust leak is acting like a venturi and sucking in cold air, fix the leak?

 

I dunno

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The heat shields are to keep the heat IN. Many folks that have installed aftermarket non-shielded headers have encountered this code - header wrap almost always solves it.

 

so it whould be the cats that are to cold ? or just not the temp the ecu whants to see we are pricing out what it whould take to replace all heat shieds on one of theese cars to get a idea if its even fesabble to fight thiss code or leave it be

 

The cats are too cold to operate efficiently. The ECU doesn't know the temp - it only knows they aren't working properly. The catalyst reaction requires a high temperature to work so if the cats drop below a critical operating temperature they simply don't function well enough and the ECU sees unburned hydrocarbons at the rear sensor - tripping the code.

 

Replacing the heat shields is probably not feasible. I don't believe you can buy them separately. A high quality header wrap or woven fiberglass insulation would do the trick - wire tied in place with stainless wire.

 

GD

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Exhaust leak acting creating venturi effect sucking air in? OK so how do you detect leak? Read earlier that SeaFoam white smoke burnoff was a great way to detect leaks but that presumes that the smoke is exiting the pipe.

I am confused

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how does the catalyst reaction get shut down? too lean? too rich? Seems like it's an a/f thing more than ambient air temps. Don't' these cars work at -30F as well as 113F? Not saying some control of the system to normalize temps wouldn't be ideal, but it seems it would be much too sensitive if the loss of a heat shield caused a problem. I'd think you'd pop 420 codes on every rainy day with cool water splashing up on the exhaust.

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Exhaust leak acting creating venturi effect sucking air in? OK so how do you detect leak? Read earlier that SeaFoam white smoke burnoff was a great way to detect leaks but that presumes that the smoke is exiting the pipe.

I am confused

 

yeah, pretty unlikely, just trying to dream up some way the exhaust would be too cool. IIRC in the 'old days' there was a cadillac that pumped fresh air in the with the exhaust to dilute the pollutant concentration to pass tailpipe tests. cheaters lol!

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how cold is it in summer where you are?

 

I kinda don't see how ambient temps have much to do with this. Those heat shields are partly to prevent hot exhaust parts from setting fire to grass if the car is parked off-pavement. Also to shield nearby stuff like oil filters, wires, cables w'ever.

 

if an exhaust leak is acting like a venturi and sucking in cold air, fix the leak?

 

I dunno

 

In some places heat shields are used to keep heat away from other components, but they are also have the effect of keeping heat IN the exhaust system, by insulating the pipes from outside air.

Internal temp of the cats has to be around 600*F before the catalyst reaction starts to happen. Nominal temp is going to be around 750 - 850*. Below that the reaction doesn't happen fast enough, and the gases coming out of the cat may be too low in oxygen content. The heat shields help keep heat in the pipes, which helps to regulate the operation and efficiency of the catalyst.

Too hot and the metals that cause the reaction will melt and can clog the cat or just get flung out the back. Either way, overheating means the cat doesn't work as well as it should.

The ECU varies fuel mixture to help control cat temps. The changes happen hundreds of times per second, and the front O2 sensor reports these mixture changes back to the ECU. As a result lazy front O2 sensor will affect cat temperature, and that will be reflected in rear O2 sensor readings, which can then trigger a P0420.

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I just think; if there's a car that was working, lost a heat shield, and started throwing 420 codes immediately - then was repaired with some heat wrap or a replacement shield - and afterwards started NOT throwing 420 codes, that that car is likely going to have another problem related to A/F within weeks.

 

Maybe I just need more education but I doubt the heat shields are a significant part of the cat function. There must be 100s of thousands of cars that have had various heat shields rust away/fall off on the roads with no significant reduction in exhaust system emissions function.

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so the thery is wrong had a 03 forester with all heat sheilds and shrouds intact and set the 420 code cleared it and it set it agian have a new thery that the cars are running to lean and there is not enuff feul left over to get cats hot the more lean it is the sooner it sets the 420 every one of theese moters i pull a plug on the plugs are very lean burning i think the feul injection is the problem to small for the engine dissplacment i do know that the more left over feul in exhaust the hotter the cats run

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It's not that simple - as I posted in my first post there are multiple causes and they generally work in conjunction but not always.

 

A weak cat coupled with missing heat shields may set the code - replace the heat shields and the code may not come back for years if at all.

 

There is not a hard and fast rule here - the system must be treated as a whole. If replacing some heat shields or adding some header wrap brings the system back into a workable state then it's prudent to do so vs. cost of replacement cats.

 

The key to repairing these codes is knowing how the catalyst system works so you can spot problems that affect it. At the end of the day you might just end up replacing the cats and sensors. But that's often not required in all cases.

 

I've had pretty good luck with installing aftermarket cat's from ebay - just generic inline units from reputable sellers on ebay. I think the last one I did was on a 4-runner and the cat was stolen - cost $75 shipped and I welded up a new section.... Dealer wanted $750 for that pipe and cat section. Hasn't thrown any codes or complained in any way.

 

GD

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so the thery is wrong had a 03 forester with all heat sheilds and shrouds intact and set the 420 code cleared it and it set it agian have a new thery that the cars are running to lean and there is not enuff feul left over to get cats hot the more lean it is the sooner it sets the 420 every one of theese moters i pull a plug on the plugs are very lean burning i think the feul injection is the problem to small for the engine dissplacment i do know that the more left over feul in exhaust the hotter the cats run

 

 

 

if you can get freezeframe data (that's what my Innova scanner call it), look at fuel trims, you may see that the ECU is pulling the fuel. large negative, maybe 2 digit negative, LTFTs. I dunno, but it seems to me a marginal front O2 or maybe a marginal MAF could 'fool' the ecu into thinking it needs to pull fuel.

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if you can get freezeframe data (that's what my Innova scanner call it), look at fuel trims, you may see that the ECU is pulling the fuel. large negative, maybe 2 digit negative, LTFTs. I dunno, but it seems to me a marginal front O2 or maybe a marginal MAF could 'fool' the ecu into thinking it needs to pull fuel.

So is it just coincidence or my wife's driving patterns (easier on the gas pedal) having anything to do with when codes occur? I seem to be code king around here.

To get freeze frame, do I need to get readings when the codes occur?

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So is it just coincidence or my wife's driving patterns (easier on the gas pedal) having anything to do with when codes occur? I seem to be code king around here.

To get freeze frame, do I need to get readings when the codes occur?

 

I'm no expert about this stuff for certain. Maybe other scanners use a different term. On my old Innova 3100a scanner, if I get a single code, FF shows in the display and I push the FF button, then scroll through the listings. It shows stuff like the speed when the that code was set, the coolant temp, etc. and the Short Term and LOng Term fuel trims.

 

If there's 2-3 codes, FF is only avail;able for one of the codes.

 

mine looks like the one on the left in this pic - you can see the term FreezeFrame in the display and the FF button on the panel;

3100A_COMPARE_3100C-640x.jpg

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still driving me nuts two more yesterday a 99 forester twin cam 420 and a 97 legacy sedan 420 both full heat shields and no exhaust leaks thiss puts the total over 50 cars all 420 all 97-05 dosent seem to matter 2.2 2.5d 2.51 2.53 all 420 have had customers change both catts and 02 sensers but still the same to many cars with same problem i think subarus ecus are calibrated poorly it seems they turn on the 420 code when they change elavation drasticaly pull the pass or up to ski hill i still have no solution for thiss and have had to tell customers that i have no fix and its a subaru problem is very frustrating

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still driving me nuts two more yesterday a 99 forester twin cam 420 and a 97 legacy sedan 420 both full heat shields and no exhaust leaks thiss puts the total over 50 cars all 420 all 97-05 dosent seem to matter 2.2 2.5d 2.51 2.53 all 420 have had customers change both catts and 02 sensers but still the same to many cars with same problem i think subarus ecus are calibrated poorly it seems they turn on the 420 code when they change elavation drasticaly pull the pass or up to ski hill i still have no solution for this and have had to tell customers that i have no fix and its a subaru problem is very frustrating

Advise customers that this usually happens to people with high IQs. They will thank you and may even question why they didn't experience it sooner!:burnout:

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still driving me nuts two more yesterday a 99 forester twin cam 420 and a 97 legacy sedan 420 both full heat shields and no exhaust leaks thiss puts the total over 50 cars all 420 all 97-05 dosent seem to matter 2.2 2.5d 2.51 2.53 all 420 have had customers change both catts and 02 sensers but still the same to many cars with same problem i think subarus ecus are calibrated poorly it seems they turn on the 420 code when they change elavation drasticaly pull the pass or up to ski hill i still have no solution for thiss and have had to tell customers that i have no fix and its a subaru problem is very frustrating

 

Are they putting something weird in the gas?

 

Does E10 or E15 (added as an oxygenator) leave too much O2 in the exhaust?

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My SOA local dealer csr blamed the winter fuel additives here in the northeast damaging the cats.

Obviously soa could track their warranty and other repairs so a pattern might be able to be detected if there were regional statistics to support this theory.

Not sure that soa would give this information up though.

Any members down south or others without winter additives experiencing the dreaded 0420?

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Are they putting something weird in the gas?

 

Does E10 or E15 (added as an oxygenator) leave too much O2 in the exhaust?

 

 

 

good point, there is a product promoted around here called RXP that 'seems' helpful for some individuals. Others seem to use it prentatively/regularly every 6 months or w'ever.. I haven't needed to try it out, but it seems highly regarded. But, I live in a non-attaiment area an we have had 10% ethanol for a long time and I have not noticed, nor are there 'rumors' or 'local legends' of it being the cause of emissions failures GENERALLY.

 

But the situation does the beg the question if something has JUST changed. I I wonder if Ivan can check with other local shops to confirm a rash of issues across years/models of cars.

 

There has been some noise made about us going to a 15% ethanol - folks are really concerned about that.

 

OH - I just remembered! I wonder if the warm temeratures is causing some phase separation or other problems with the gas/ethanol?

 

Ed Wallace is the local 'car talk' guy and he may have some info on the ethanol phase separation. I wonder if the cars Ivan is seeing sit in the heat unused for some period of time, then throw codes? There must be some common factor here if he has noticed a drastic increase.

 

**********Later-model cars and trucks were supposed to have been re-engineered to mitigate the corrosive properties of the E-10 ethanol-laced fuel. Ed Wallace, writing in Business Week, finds that this is not necessarily true. “Not only is ethanol proving to be a dud as a fuel substitute, but there is increasing evidence that it is destroying engines in large numbers.” He goes on: “It now appears that in just a few years since the government forced ethanol use on the country, engine and fuel system failures caused by ethanol are causing major damage to more and more new and used vehicles.” Wallace concludes: “Sadly, when a truly bad idea is exposed today, Washington’s answer is to double-down on the bet, mandate more of the same, and make the problem worse. Only this time around motorists will be able to gauge the real cost of ethanol when it comes time to fix their personal cars.”

Ethanol has two other properties that further complicate the process. Ethanol and gasoline do not bond chemically. They simply coexist in the fuel system in an “oil and vinegar” relationship. While ethanol may hate gasoline, it loves water. The term to describe this is “hygroscopic,” or “water soluble.” Ethanol attracts and absorbs water. As long as the amount of water in the fuel system is small, this can be a good thing: In the winter it limits the possibility of a fuel line freeze-up. However, as the water content gets higher, the new ethanol/water compound sinks to the bottom of the fuel tank. This process is called “phase separation.”

If we continually drive our cars (or cut our grass every week or so) these ethanol-unique characteristics will not normally be an issue. But after about 90 days (the shelf life of E-10 gasoline), problems begin to manifest. The result: “bad gas.” The engine won’t start or there will be “missing” or “sputtering” problems. This is the reason you don’t want to leave gas containing ethanol in the lawn mower over the winter.

Because of the separation and corrosion problems, ethanol cannot be transported through pipelines. It requires its own separate and costly distribution channel dominated by rail and trucks to keep it apart from the gasoline as long as possible before retail.

***************************************

 

 

from; http://www.thefreemanonline.org/features/government-moonshine/

 

**

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so two more a 03 forester and a 99 outback yesterday 420 420 thats over 55 cars here with 420 codes and havent got one to shut off light yet i'm thinking pluged injectors making it to lean or just two small of injectors

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so two more a 03 forester and a 99 outback yesterday 420 420 thats over 55 cars here with 420 codes and havent got one to shut off light yet i'm thinking pluged injectors making it to lean or just two small of injectors

 

is there anyway the - uh - Province or government could test gasoline samples from several of the affected cars?

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but its not just cars in my area on is from edmonton over 800 kms away and 420 other is from vancouver 600 kms away from all over the map and differnt gas stations and some run only premium feul some run crap feul i dont think its the gas I think that its to lean or ecu calibration problem i do get some very dirty feul fillters here still no solution as of yet :banghead:

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but its not just cars in my area on is from edmonton over 800 kms away and 420 other is from vancouver 600 kms away from all over the map and differnt gas stations and some run only premium feul some run crap feul i dont think its the gas I think that its to lean or ecu calibration problem i do get some very dirty feul fillters here still no solution as of yet :banghead:

 

 

Just remember, the system will try to make changes, and can be fooled by mis-information. Either from air/vacuum/exhaust leaks or from bad/marginal sensors/parts.

 

for example, if worn spark plugs are missing, then unburned fuel leaves the combustion chamber, the front O2 sensor may signal a 'rich' condition, then the ECU leans out the injectors. Then that may lead to high nox, more misfires or ???????

 

Is there year or model in common? are they all PZEV cars? H4 and H6es?

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all 2.5 s mostly the 2.51 from 99-05 a few ealy ones the 2.2 seems immune to it only seen one 2.2 and was 01 phase two most have had engines rebuilt and all new compnents and good comp and tune most i have been the only one to work on them i tried some lucas feul syestem treatment on one yesterday as a test pilot is a 03 forester had turned light on will see if that helps it at all i still think its a lean problem pluged injectors i think

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I'm under the impression Techron gas treatment might actually help with injectors. Maybe experiment with it in a 'test' vehicle as well.

 

any rumors from other shops about this epidemic of 420s?

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